Quercetin reduces inflammatory pain: inhibition of oxidative stress and cytokine production

Quercetin and L-Arginine Ameliorated the Deleterious Effects of Copper Oxide Nanoparticles on the Liver of Mice Through Anti-inflammatory and Anti-apoptotic Pathways

The widespread use and applications of copper oxide nanoparticles (CuO NPs) in daily life make human exposure to these particles inevitable. This study was carried out to investigate the deteriorations in hepatic and serum biochemical parameters induced by CuO NPs in adult male mice and the potential ameliorative effect of L-arginine and quercetin, either alone or in combination. Seventy adult male mice were equally allocated into seven groups: untreated group, L-arginine, quercetin, CuO NPs, arginine + CuO NPs, quercetin + CuO NPs, and quercetin + arginine + CuO NPs. Treating mice with CuO NPs resulted in bioaccumulation of copper in the liver and consequent liver injury as typified by elevation of serum ALT activity, reduction in the synthetic ability of the liver indicated by a decrease in the hepatic arginase activity, and serum total protein content. This copper accumulation increased oxidative stress, lipid peroxidation, inflammation, and apoptosis as manifested by elevation in malondialdehyde, nitric oxide, tumor necrosis factor-α, the expression level of caspase-3 and bax quantified by qPCR, and the activity of caspase-3, in addition to the reduction of superoxide dismutase activity. It also resulted in severe DNA fragmentation as assessed by Comet assay and significant pathological changes in the liver architecture. The study proved the efficiency of quercetin and L-arginine in mitigating CuO NPs-induced sub-chronic liver toxicity due to their antioxidant, anti-inflammatory, and anti-apoptotic properties; ability to inhibit DNA damage; and the potential as good metal chelators. The results of histopathological analysis confirmed the biochemical and molecular studies.

Highly selective and sensitive molecularly imprinted sensors for the electrochemical assay of quercetin in methanol extracts of Rubus sanctus and Fragaria vesca

Quercetin (QUE) is a powerful antioxidant and one of the common phenolic compounds found in plants, vegetables, and fruits, which has shown many pharmacological activities. The complex nature of the matrix in which QUE is found and its importance and potential uses in diverse applications force the researchers to develop selective and sensitive sensors. In the present work, a novel molecularly imprinted polymer (MIP)-based electrochemical sensor was fabricated for the selective and sensitive determination of the QUE in plant extracts and food supplements. Tryptophan methacrylate (TrpMA) was chosen as the functional monomer, whereas the photopolymerization (PP) method was applied using a glassy carbon electrode (GCE). Electrochemical and morphological characterizations of the developed sensor (TrpMA@QUE/MIP-GCE) were performed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). The linear range of the developed sensor was determined to be in the range of 1.0-25 pM, while the limit of detection (LOD) was calculated to be 0.235 pM. In conclusion, The TrpMA@QUE/MIP-GCE sensor might be classified as a promising platform for selective and sensitive determination of QUE not only in plant extracts but also in commercial food supplements because of its reliability, reproducibility, repeatability, stability, and fast response time.

Exploring the antioxidant potential of chalcogen-indolizines throughout in vitro assays

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are highly reactive molecules produced naturally by the body and by external factors. When these species are generated in excessive amounts, they can lead to oxidative stress, which in turn can cause cellular and tissue damage. This damage is known to contribute to the aging process and is associated with age-related conditions, including cardiovascular and neurodegenerative diseases. In recent years, there has been an increased interest in the development of compounds with antioxidant potential to assist in the treatment of disorders related to oxidative stress. In this way, compounds containing sulfur (S) and/or selenium (Se) have been considered promising due to the relevant role of these elements in the biosynthesis of antioxidant enzymes and essential proteins with physiological functions. In this context, studies involving heterocyclic nuclei have significantly increased, notably highlighting the indolizine nucleus, given that compounds containing this nucleus have been demonstrating considerable pharmacological properties. Thus, the objective of this research was to evaluate the in vitro antioxidant activity of eight S- and Se-derivatives containing indolizine nucleus and different substituents. The in vitro assays 1,1-diphenyl-2-picryl-hydrazil (DPPH) scavenger activity, ferric ion (Fe3+) reducing antioxidant power (FRAP), thiobarbituric acid reactive species (TBARS), and protein carbonylation (PC) were used to access the antioxidant profile of the compounds. Our findings demonstrated that all the compounds showed FRAP activity and reduced the levels of TBARS and PC in mouse brains homogenates. Some compounds were also capable of acting as DPPH scavengers. In conclusion, the present study demonstrated that eight novel organochalcogen compounds exhibit antioxidant activity.

From Plant to Chemistry: Sources of Antinociceptive Non-Opioid Active Principles for Medicinal Chemistry and Drug Design

Pain is associated with many health problems and a reduced quality of life and has been a common reason for seeking medical attention. Several therapeutics are available on the market, although side effects, physical dependence, and abuse limit their use. As the process of pain transmission and modulation is regulated by different peripheral and central mechanisms and neurotransmitters, medicinal chemistry continues to study novel ligands and innovative approaches. Among them, natural products are known to be a rich source of lead compounds for drug discovery due to their chemical structural variety and different analgesic mechanisms. Numerous studies suggested that some chemicals from medicinal plants could be alternative options for pain relief and management. Previously, we conducted a literature search aimed at identifying natural products interacting either directly or indirectly with opioid receptors. In this review, instead, we have made an excursus including active ingredients derived from plants whose mechanism of action appears from the literature to be other than the modulation of the opioid system. These substances could, either by themselves or through synthetic and/or semi-synthetic derivatives, be investigated in order to improve their pharmacokinetic characteristics and could represent a valid alternative to the opioid approach to pain therapy. They could also be the basis for the study of new mechanisms of action in the approach to this complex and disabling pathology.

Research advances of Zanthoxylum bungeanum Maxim. polyphenols in inflammatory diseases

Zanthoxylum bungeanum Maxim., commonly known as Chinese prickly ash, is a well-known spice and traditional Chinese medicine ingredient with a rich history of use in treating inflammatory conditions. This review provides a comprehensive overview of the botanical classification, traditional applications, and anti-inflammatory effects of Z. bungeanum, with a specific focus on its polyphenolic components. These polyphenols have exhibited considerable promise, as evidenced by preclinical studies in animal models, suggesting their therapeutic potential in human inflammatory diseases such as ulcerative colitis, arthritis, asthma, chronic obstructive pulmonary disease, cardiovascular disease, and neurodegenerative conditions. This positions them as a promising class of natural compounds with the potential to enhance human well-being. However, further research is necessary to fully elucidate their mechanisms of action and develop safe and effective therapeutic applications.

Network Pharmacology and In vitro Experimental Verification to Explore the Mechanism of Chaiqin Qingning Capsule in the Treatment of Pain

BACKGROUND

Chaiqin Qingning capsule (CQQNC) has been used to relieve pain in practice. However, the active components, pain targets, and molecular mechanisms for pain control are unclear.

OBJECTIVE

To explore the active components and potential mechanisms of the analgesic effect of CQQNC through network pharmacology and in vitro experiments.

METHODS

The main active components and the corresponding targets of CQQNC were screened from the TCMSP and the SwissTargetPrediction databases. Pain-related targets were selected in the OMIM, Gene- Cards, and DrugBank databases. These targets were intersected to obtain potential analgesic targets. The analgesic targets were imported into the STRING and DAVID databases for protein-protein interaction (PPI), gene ontology (GO) function enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. Cytoscape software (V3.7.1) was used to construct an active component-intersection network. Finally, the key components were docked with the core targets. The analgesic mechanism of CQQNC was verified by RAW264.7 cell experiment.

RESULTS

30 active CQQNC components, 617 corresponding targets, and 3,214 pain-related target genes were found. The main active components were quercetin, kaempferol, and chenodeoxycholic acid etc. The key targets were ALB, AKT1, TNF, IL6, TP53, IL1B, and SRC. CQQNC can exert an analgesic effect through PI3K-Akt, MAPK signaling pathways, etc. Molecular docking showed that these active components had good binding activities with key targets. The results of in vitro experiments showed that CQQNC could exert antiinflammatory and analgesic effects through MAPK/AKT/NF-kB signaling pathways.

CONCLUSION

CQQNC exerts pain control through inhibiting MAPK/AKT/NF-kB signaling pathways.

The effect of quercetin supplementation on clinical outcomes in COVID-19 patients: A systematic review and meta-analysis

Coronavirus disease (COVID-19) affects both the respiratory system and the body as a whole. Natural molecules, such as flavonoid quercetin, as potential treatment methods to help patients combat COVID-19. The aim of this systematic review and meta-analysis is to give a comprehensive overview of the impact of quercetin supplementation on inflammatory factors, hospital admission, and mortality of patients with COVID-19. The search has been conducted on PubMed, Scopus, Web of Science, EMBASE, and the Cochrane Library using relevant keywords until August 25, 2023. We included randomized controlled trials (RCTs) comparing COVID-19 patients who received quercetin supplementation versus controls. We included five studies summarizing the evidence in 544 patients. Meta-analysis showed that quercetin administration significantly reduced LDH activity (standard mean difference (SMD): -0.42, 95% CI: -0.82, -0.02, I 2 = 48.86%), decreased the risk of hospital admission by 70% (RR: 0.30, 95% CI: 0.14, 0.62, I 2 = 00.00%), ICU admission by 73% (RR: 0.27, 95% CI: 0.09, 0.78, I 2 = 20.66%), and mortality by 82% (RR: 0.18, 95% CI: 0.03, 0.98, I 2 = 00.00%). No significant changes in CRP, D-dimmer, and ferritin were found between groups. Quercetin was found to significantly reduce LDH levels and decrease the risk of hospital and ICU admission and mortality in patients with COVID-19 infection.

Quercus floribunda Lindl. Ex A. Camus; a tremendous remedy against inflammation and associated symptoms

Crude extracts prepared from aerial parts and nut galls of Quercus floribunda Lindl. Ex. A. Camus were evaluated for phytochemical screening, in vitro antioxidant, and in vivo analgesic, anti-inflammatory and antipyretic activities. Various solvents including methanol (M), acetone (A), distilled water (DW), distilled water + methanol (DWM) were used for extraction. Highest total phenolic (66.9 ± 0.05 μg GAE/mgE) and flavonoid content (38.4 ± 0.72 μg QE/mgE) were measured in QFAA extract by colorimetric methods. Cumulative maximum concentrations of polyphenols were quantified in QFMG, QFAA, and QFMA extracts i.e. 19.036, 15. 574 and 11.647 μg/mg of extract by RP-HPLC analysis. From aerial parts extracts, apentacyclic tritepenoid, glutinol was isolated using column chromatography techniques and structure was elucidated using spectroscopic techniques. QFDWMA (205.5 ± 0.56 μg AAE/mg of extract) showed highest total reducing power while highest total antioxidant capacity (207.1 ± 0.49 AAE/mg of extract) and free radical scavenging potential (96.1 ± 0.42%) were observed in QFAA extract. QFAA extract showed significant (p ≤ 0.001) analgesic potential in different pain models i.e. hot plate method, cold plate method, Haffner's tail clip method and acetic acid induced writhing assay having 50.20%, 62.07%, 57.26% and 70.49% analgesia respectively at 300 mg/kg. QFAA extract showed maximum anti-inflammatory activity in croton oil induced edema (68.83%) and in carrageenan induced paw edema models (72.32%) at 300 mg/kg concentration. QFAA extract markedly reduced the rectal temperature at 300 mg/kg concentration, in brewer's yeast induced pyrexia model. Detailed investigations can be executed in future to determine the molecular mechanisms of these pharmacological attributes.

Exploitation of Quercetin's Antioxidative Properties in Potential Alternative Therapeutic Options for Neurodegenerative Diseases

Oxidative stress (OS) is a condition in which there is an excess of reactive oxygen species (ROS) in the body, which can lead to cell and tissue damage. This occurs when there is an overproduction of ROS or when the body's antioxidant defense systems are overwhelmed. Quercetin (Que) is part of a group of compounds called flavonoids. It is found in high concentrations in vegetables, fruits, and other foods. Over the past decade, a growing number of studies have highlighted the therapeutic potential of flavonoids to modulate neuronal function and prevent age-related neurodegeneration. Therefore, Que has been shown to have antioxidant, anticancer, and anti-inflammatory properties, both in vitro and in vivo. Due to its antioxidant character, Que alleviates oxidative stress, thus improving cognitive function, reducing the risk of neurodegenerative diseases. On the other hand, Que can also help support the body's natural antioxidant defense systems, thus being a potentially practical supplement for managing OS. This review focuses on experimental studies supporting the neuroprotective effects of Que in Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and epilepsy.

The Potential of Ameliorating COVID-19 and Sequelae From Andrographis paniculata via Bioinformatics

The current coronavirus disease 2019 (COVID-19) outbreak is alarmingly escalating and raises challenges in finding efficient compounds for treatment. Repurposing phytochemicals in herbs is an ideal and economical approach for screening potential herbal components against COVID-19. Andrographis paniculata, also known as Chuan Xin Lian, has traditionally been used as an anti-inflammatory and antibacterial herb for centuries and has recently been classified as a promising herbal remedy for adjuvant therapy in treating respiratory diseases. This study aimed to screen Chuan Xin Lian's bioactive components and elicit the potential pharmacological mechanisms and plausible pathways for treating COVID-19 using network pharmacology combined with molecular docking. The results found terpenoid (andrographolide) and flavonoid (luteolin, quercetin, kaempferol, and wogonin) derivatives had remarkable potential against COVID-19 and sequelae owing to their high degrees in the component-target-pathway network and strong binding capacities in docking scores. In addition, the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that the PI3K-AKT signaling pathway might be the most vital molecular pathway in the pathophysiology of COVID-19 and long-term sequelae whereby therapeutic strategies can intervene.

The Emerging Role of Quercetin in the Treatment of Chronic Pain

Despite much research efforts being devoted to designing alternative pharmacological interventions, chronic pain remains to be an unresolved clinical problem. Quercetin, a compound that belongs to the flavonoids family, is abundantly found in fruits and vegetables. Emerging evidence indicates that quercetin possesses anti-nociceptive effects in different rodent models of chronic pain, including inflammatory pain, neuropathic pain and cancer pain. In this review, we summarize the mechanisms underlying the analgesic effect of quercetin in preclinical studies. These studies showed that quercetin exerts potent analgesic effects against chronic pain via suppressing neuroinflammation and oxidative stress as well as modulation of synaptic plasticity, GABAergic system, and opioidergic system. Considering that the safety of quercetin is well established, it has great potential for clinical use in pain treatment.

Resolvin D1 alleviates mechanical allodynia via ALX/FPR2 receptor targeted NLRP3/ERK signaling in a neuropathic pain model

The current study aimed to investigate the role and underlying mechanism of Resolvin D1 (RvD1) alleviating spinal nerve ligation (SNL)-induced neuropathic pain (NP) and its interplay with regulatory cascades of NLRP3 inflammasome. Sprague-Dawley male rat model of SNL-stimulated NP was established, which were pre-treated with different doses of RvD1, WRW4 (ALX/FPR2 inhibitor) or U0126 (ERK inhibitor) for three successive days following the operation. Pain behavior was assessed by measuring changes in the mechanical sensitivity of the hind paws during an observation period of 7 consecutive days. The spinal cord (SC) and dorsal root ganglions (DRGs) tissues were collected on postoperative day 7. Immunohistochemistry (IHC) and western blot were performed to determine the expression levels of NLRP3 inflammasome complex, ALX/FPR2 receptor and extracellular signal-related kinase (ERK). The pro-inflammatory mediators (IL-1β and IL-18) were measured by enzyme-linked immunosorbent assay (ELISA). The results showed that RvD1 could alleviate mechanical allodynia significantly in the SNL-induced NP rat model. Also, RvD1 inhibited the expression of p-ERK, the NLRP3 inflammasomes complex and its corresponding downstream pro-inflammatory mediators which were significantly enhanced in the SC and DRGs of the rat of SNL model. While these changes were partially reversed by pre-administration of WRW4 and further strengthened by co-treated with U0126. Our results suggest that RvD1 dependent on ALX/FPR2 may have an analgesic and anti-inflammatory influence on SNL-induced NP driven by inhibiting NLRP3 inflammasome via ERK signaling pathway. These data also provide strong support for the recent modulation of neuro-inflammatory priming and highlight the potential for specialized pro-resolving mediators (SPMs) as novel therapeutic avenues for NP.

Antinociceptive effects of minor cannabinoids, terpenes and flavonoids in Cannabis

Cannabis has been used for centuries for its medicinal properties. Given the dangerous and unpleasant side effects of existing analgesics, the chemical constituents of Cannabis have garnered significant interest for their antinociceptive, anti-inflammatory and neuroprotective effects. To date, Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) remain the two most widely studied constituents of Cannabis in animals. These studies have led to formulations of THC and CBD for human use; however, chronic pain patients also use different strains of Cannabis (sativa, indica and ruderalis) to alleviate their pain. These strains contain major cannabinoids, such as THC and CBD, but they also contain a wide variety of cannabinoid and noncannabinoid constituents. Although the analgesic effects of Cannabis are attributed to major cannabinoids, evidence indicates other constituents such as minor cannabinoids, terpenes and flavonoids also produce antinociception against animal models of acute, inflammatory, neuropathic, muscle and orofacial pain. In some cases, these constituents produce antinociception that is equivalent or greater compared to that produced by traditional analgesics. Thus, a better understanding of the extent to which these constituents produce antinociception alone in animals is necessary. The purposes of this review are to (1) introduce the different minor cannabinoids, terpenes, and flavonoids found in Cannabis and (2) discuss evidence of their antinociceptive properties in animals.

Therapeutic and prophylactic effect of flavonoids in post-COVID-19 therapy

The high incidence of post-covid symptoms in humans confirms the need for effective treatment. Due to long-term complications across several disciplines, special treatment programs emerge for affected patients, emphasizing multidisciplinary care. For these reasons, we decided to look at current knowledge about possible long-term complications of COVID-19 disease and then present the effect of flavonoids, which could help alleviate or eliminate complications in humans after overcoming the COVID-19 infection. Based on articles published from 2003 to 2021, we summarize the flavonoids-based molecular mechanisms associated with the post-COVID-19 syndrome and simultaneously provide a complex view regarding their prophylactic and therapeutic potential. Review clearly sorts out the outcome of post-COVID-19 syndrome according particular body systems. The conclusion is that flavonoids play an important role in prevention of many diseases. We suggest that flavonoids as critical nutritional supplements, are suitable for the alleviation and shortening of the period associated with the post-COVID-19 syndrome. The most promising flavonoid with noteworthy therapeutic and prophylactic effect appears to be quercetin.

Pimenta pseudocaryophyllus (Gomes) Landrum extract inhibits inflammatory pain in mice: targeting neutrophil recruitment, oxidative stress, and cytokine production

Pimenta pseudocaryophyllus (Gomes) Landrum is a Brazilian native plant. The mechanisms by which it promotes analgesia are unknown. We demonstrated the analgesic effect of P. pseudocaryophyllus dried extract (3 mg/kg; i.p.) in the following models of inflammatory pain (maximal inhibition): phenyl-p-benzoquinone (89%), formalin (72% - 1st phase and 96% - 2nd phase for flinches, and 50% - 1st phase and 71% - 2nd phase for licking behavior), complete Freund's adjuvant (95% - flinches and 33% - licking behavior), and carrageenin (56% - mechanical and 85% - thermal hyperalgesia) without motor impairment. Its analgesic effect depends on inhibiting neutrophil recruitment (95% - histopathology, 83% - myeloperoxidase activity, and 80% - LysM-eGFP mice), oxidative stress (86% - GSH and 98% - superoxide anion), and cytokine production (35% - IL-33, 80% - TNF-α, and 95% - IL-1β). The present study advances in understanding the analgesic mechanisms of P. pseudocaryophyllus.

Flavonoid-rich fraction from Croton blanchetianus (Euphorbiaceae) leaves exerts peripheral and central analgesic effects by acting via the opioid and cholinergic systems

The ethanolic extract from Croton blanchetianus leaves has been shown to have antinociceptive activity in mice. Here, we investigated the antinociceptive activity of an ethyl acetate fraction (EAF) from this extract in mice and the possible pathways involved in the analgesic effect. Adverse effects on behavior and motor coordination were also evaluated. The EAF was characterized by liquid chromatography coupled with mass spectrometry and evaluated (12.5, 25, and 50 mg/kg per os) in the acetic acid-induced abdominal writhing, formalin, hot plate, and tail immersion assays. Naloxone, atropine, glibenclamide, prazosin, or yohimbine was pre-administered to mice to investigate the involved pathways in the formalin test. The open-field, rotarod, and elevated plus-maze tests were used to assess behavior and locomotion. The main components of the EAF were quercetin-3-O-(2-rhamnosyl) rutinoside, hyperoside, quercetin rutinoside pentoside, and quercetin hexoside deoxyhexoside. EAF showed antinociceptive effects in all models and was effective against both neurogenic and inflammatory pain. The reversion of the effects in the formalin test by naloxone and atropine revealed that the EAF acted via the opioid and cholinergic systems. In the open-field test, the behavior of the animals treated with the EAF was like that of control, except at the highest dose, when hypnosis, eyelid ptosis, decreased walking, hygiene, and rearing behaviors were observed. No muscle relaxant effect was observed, but an anxiogenic effect was observed at all doses. This study provides new scientific evidence on the pharmacological properties of C. blanchetianus leaves and their potential for the development of phytomedicines with analgesic properties.

In vivo anti-inflammatory and antinociceptive effects, and in vitro antioxidant, antiglycant and anti-neuroinflammatory actions of Syzygium malaccense

Syzygium malaccense is popularly used to treat inflammation and pain-related ailments. The species was assessed regarding its antioxidant, antiglycant, anti-inflammatory, including anti-neuroinflammatory, and antinociceptive activities. Different models were employed to measure S. malaccense extract (ESM) antioxidant activity. The antiglycant activity was determined using the glucose-induced protein glycation model. LPS-induced neuroinflammation on murine BV-2 microglial cell line was used for anti-neuroinflammatory activity evaluation. The croton oil-induced ear edema test was accomplished to evaluate the in vivo anti-inflammatory activity. Acetic acid-induced writhing together with formalin-induced paw licking assays were performed to evaluate the antinociceptive potential. Finally, the chemical characterization was accomplished by a UHPLC-MS analysis. ESM presented relevant antioxidant and antiglycant activity. NO production by BV-2 cells was reduced, indicating the relevant neuroprotective activity. ESM significantly decreased the mice ear edema induced by croton oil and the nociceptive stimulus induced by acetic acid and formalin by central and peripheral mechanisms. The flavonoids myricitrin, myricetin and quercetin were identified and, as far as we know, the alkaloid reserpine was reported in the species for the first time. The antioxidant and antiglycant potential of ESM, may be related to the in vivo anti-inflammatory and antinociceptive effects, and to the in vitro neuroinflammation inhibition.

Quercetin decreases the antinociceptive effect of diclofenac in an arthritic gout-pain model in rats

OBJECTIVE

To analyse the antinociceptive interaction between quercetin (QUER) and diclofenac (DIC) in experimental arthritic gout-pain.

METHODS

The antinociceptive effect of DIC and QUER alone and in combination were evaluated using an arthritic gout-pain model. Pain was induced through intra-articular administration of uric acid in the rats and the treatments were administered 2 h later. Additionally, the cyclooxygenase (COX) activity was determined in rats treated with DIC, QUER and their combination.

KEY FINDINGS

DIC induced a maximal effect of 69.7 ± 2.7% with 3.1 mg/kg; whereas QUER only produced 17.6 ± 2.6% with the maximal dose (316 mg/kg). Ten of twelve DIC + QUER combinations showed a lesser antinociceptive effect than DIC alone did (P < 0.05). Moreover, DIC reduced total-COX (70.4 ± 1.3 versus 52.4 ± 1.8 and 77.4 ± 9.0 versus 56.1 ± 1.3, P < 0.05) and COX-2 (60.1 ± 1.0 versus 42.4 ± 1.8 and 58.1 ± 2.4 versus 48.7 ± 1.3, P < 0.05) activity after 1 and 3 h, respectively. Nevertheless, only the COX-2 activity induced by DIC was prevented in the presence of QUER (63.2 ± 3.0 versus 60.1 ± 1.0 and 56.6 ± 1.3 versus 58.1 ± 2.4 at 1 and 3 h, respectively).

CONCLUSIONS

All these data demonstrated that the simultaneous administration of QUER + DIC produces an unfavorable interaction on the antinociceptive effect of DIC. Therefore, this combination might not be recommendable to relieve arthritic gout-pain.

The Hydroethanolic Stem Bark Extract of Tieghemella heckelii (A.Chev.) Pierre ex Dubard (Sapotaceae) Produced N-Methyl-D-Aspartate (NMDA) Receptor-Dependent Analgesia and Attenuates Acute Inflammatory Pain via Disruption of Oxidative Stress

BACKGROUND

Tieghemella heckelii stem bark is used in African traditional medicine to treat inflammatory pain conditions. However, these biological actions of the plant have not been proven. This study investigates the phytochemical composition and the mechanisms of analgesic and anti-inflammatory actions of the hydroethanolic stem bark extract of T. heckelii (THBE).

METHODS

Phytochemical composition of THBE was investigated using qualitative and quantitative phytochemical analyses. Anti-inflammatory activity was evaluated using the carrageenan-induced paw oedema assay. Analgesic activity was evaluated using hot plate and acetic acid-induced writhing assays. Mechanism of analgesic action was determined using pharmacological antagonist such as naloxone, atropine, flumazenil, nifedipine, or ketamine. Test agents were administered orally as follows: Tween 80 (5%) (control), diclofenac sodium (DS) 10/tramadol 9 mg/kg (standard), or THBE 10, 100, and 450 mg/kg. Glutathione peroxidase (GPx), superoxide dismutase (SOD), and lipid peroxidation levels were also measured.

RESULTS

THBE which contained 58.45% saponins, 229.04 ± 0.049 GAE mg/g phenolic compounds,and 0.482 ± 0.0028 QE mg/g flavonoids produced (p < 0.5) anti-inflammatory effect of 56.22% and analgesia of 330 ± 72% and 50.4% in the hot plate and writhing assays, respectively, at 10 mg/kg and inhibited oxidative stress by GPx and SOD elevation in rats during inflammation. Ketamine significantly blocked the analgesia of THBE, indicating NMDA receptor-dependent analgesic action. Whereas, naloxone, atropine, nifedipine, and flumazenil could not antagonize the analgesic action of THBE.

CONCLUSION

These results show that THBE produced potent anti-inflammatory effect via disruption of oxidative stress and also generated NMDA receptor-dependent analgesia.

Phytochemical screening of aqueous leaf extract of Blighia sapida K.D. Koenig (Sapindaceae) and its analgesic property in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Blighia sapida is traditionally used in treating intercostal pain, psychosis, stomach ache, back pain, and skin diseases. However, there is limited information on the scientific basis for its use traditionally in the treatment of pain.

AIM OF STUDY

To identify the major constituents in the aqueous leaf extract of Blighia sapida (AEBS) and to assess its analgesic properties in mice.

MATERIALS AND METHODS

Bioactive compounds were identified and quantified in AEBS by High Performance Liquid Chromatography/Photodiode Array Detector (HPLC/DAD). Analgesic activity of AEBS was assessed at doses of 125, 250, and 500 mg/kg p.o., using animal models.

RESULTS

Chlorogenic acid, saponins, tannins, caffeic acid, quercetin, gallic acid, pyrogallol, quinine, caffeine, and nicotine were identified. At doses 250 mg/kg (p < 0.05) and 500 mg/kg (p < 0.01), AEBS significantly inhibited acetic acid induced writhing in comparison with the control. It also significantly inhibited pain in the inflammatory phase of the formalin induced paw licking test at 250 mg/kg (p < 0.01) and 500 mg/kg (p < 0.05) doses, in comparison with the control. It did not inhibit pain in the neurogenic phase of the formalin paw licking and in the hot plate tests.

CONCLUSION

Blighia sapida leaf extract possesses analgesic activity that is mediated by peripheral mechanisms but not through central mechanisms.

Sigma-1 receptor antagonist (BD-1063) potentiates the antinociceptive effect of quercetin in neuropathic pain induced by chronic constriction injury

Neuropathic pain is characterized by the presence of hyperalgesia and allodynia. Pharmacological treatments include the use of antiepileptics such as pregabalin or gabapentin, as well as antidepressants; however, given the role of the sigma-1 receptor in the generation and maintenance of pain, it has been suggested that sigma-1 receptor antagonists may be effective. There are also other alternatives that have been explored, such as the use of flavonoids such as quercetin. Due to the relevance of drug combinations in therapeutics, the objective of this work was to evaluate the effect of the combination of BD-1063 with quercetin in a chronic sciatic nerve constriction model using the "Surface of Synergistic Interaction" analysis method. The combination had preferable additive or synergistic effects, with BD-1063 (17.8 mg/kg) + QUER (5.6 mg/kg) showing the best antinociceptive effects. The required doses were also lower than those used individually to obtain the same level of effect. Our results provide the first evidence that the combination of a sigma-1 receptor antagonist and the flavonoid quercetin may be useful in the treatment of nociceptive behaviors associated with neuropathic pain, suggesting a new therapeutic alternative for this type of pain.

Thiazolidine Derivatives Attenuate Carrageenan-Induced Inflammatory Pain in Mice

BACKGROUND

Peripheral inflammation leads to the development of persistent thermal hyperalgesia and mechanical allodynia associated with increased expression of interleukin-1β (IL-1β) in the spinal cord. The aim of the present study was to investigate the effects of thiazolidine derivatives, 1b ([2-(2-hydroxyphenyl)-1,3-thiazolidin-4-yl](morpholin-4-yl)methanone) and 1d (2-hydroxy-4-{[2-(2-hydroxyphenyl)-1,3-thiazolidine-4-carbonyl]amino}benzoic acid), on thermal hyperalgesia, mechanical allodynia and on IL-1β expression during carrageenan-induced inflammation in the spinal cord in mice. Inflammatory pain was induced by injecting 1% carrageenan into the right hind paw of the mice.

METHODS

The animals were administered thiazolidine derivatives, 1b and 1d (1 mg/kg, 3 mg/kg, or 10 mg/kg), intraperitoneally 30 minutes before carrageenan administration. The animals' behavior was evaluated by measuring thermal hyperalgesia, mechanical allodynia, and motor coordination. The IL-1β expression was measured by enzyme-linked immunosorbent assay. Acute and sub-acute toxicity studies were conducted to evaluate the toxicity profile of compounds.

RESULTS

Treatment with the thiazolidine derivative, 1b and 1d, attenuated carrageenan-induced thermal hyperalgesia and mechanical allodynia at doses of 1 mg/kg, 3 mg/kg, and 10 mg/kg. No motor coordination deficits were observed in animals. The compounds also reduced IL-1β expression in the spinal cord of mice. Acute and sub-acute toxicity studies revealed that both compounds were safe.

CONCLUSION

The compounds exhibit promising activity against inflammatory pain due to their ability to produce anti-hyperalgesic and anti-allodynic effects and to inhibit IL-1β expression in the spinal cord.

Calming the Storm: Natural Immunosuppressants as Adjuvants to Target the Cytokine Storm in COVID-19

The COVID-19 pandemic has caused a global health crisis, with no specific antiviral to treat the infection and the absence of a suitable vaccine to prevent it. While some individuals contracting the SARS-CoV-2 infection exhibit a well coordinated immune response and recover, others display a dysfunctional immune response leading to serious complications including ARDS, sepsis, MOF; associated with morbidity and mortality. Studies revealed that in patients with a dysfunctional immune response, there is a massive cytokine and chemokine release, referred to as the ‘cytokine storm’. As a result, such patients exhibit higher levels of pro-inflammatory/modulatory cytokines and chemokines like TNFα, INFγ, IL-1β, IL-2, IL-4, IL-6, IL-7, IL-9, IL-10, IL-12, IL-13, IL-17, G-CSF, GM-CSF, MCSF, HGF and chemokines CXCL8, MCP1, IP10, MIP1α and MIP1β. Targeting this cytokine storm is a novel, promising treatment strategy to alleviate this excess influx of cytokines observed at the site of infection and their subsequent disastrous consequences. Natural immunosuppressant compounds, derived from plant sources like curcumin, luteolin, piperine, resveratrol are known to inhibit the production and release of pro-inflammatory cytokines and chemokines. This inhibitory effect is mediated by altering signal pathways like NF-κB, JAK/STAT, MAPK/ERK that are involved in the production and release of cytokines and chemokines. The use of these natural immunosuppressants as adjuvants to ameliorate the cytokine storm; in combination with antiviral agents and other treatment drugs currently in use presents a novel, synergistic approach for the treatment and effective cure of COVID-19. This review briefly describes the immunopathogenesis of the cytokine storm observed in SARS-CoV-2 infection and details some natural immunosuppressants that can be used as adjuvants in treating COVID-19 disease.

An Investigation of the Molecular Mechanisms Underlying the Analgesic Effect of Jakyak-Gamcho Decoction: A Network Pharmacology Study

Herbal drugs have drawn substantial interest as effective analgesic agents; however, their therapeutic mechanisms remain to be fully understood. To address this question, we performed a network pharmacology study to explore the system-level mechanisms that underlie the analgesic activity of Jakyak-Gamcho decoction (JGd; Shaoyao-Gancao-Tang in Chinese and Shakuyaku-Kanzo-To in Japanese), an herbal prescription consisting of Paeonia lactiflora Pallas and Glycyrrhiza uralensis Fischer. Based on comprehensive information regarding the pharmacological and chemical properties of the herbal constituents of JGd, we identified 57 active chemical compounds and their 70 pain-associated targets. The JGd targets were determined to be involved in the regulation of diverse biological activities as follows: calcium- and cytokine-mediated signalings, calcium ion concentration and homeostasis, cellular behaviors of muscle and neuronal cells, inflammatory response, and response to chemical, cytokine, drug, and oxidative stress. The targets were further enriched in various pain-associated signalings, including the PI3K-Akt, estrogen, ErbB, neurotrophin, neuroactive ligand-receptor interaction, HIF-1, serotonergic synapse, JAK-STAT, and cAMP pathways. Thus, these data provide a systematic basis to understand the molecular mechanisms underlying the analgesic activity of herbal drugs.

Quantification of computational fluid dynamics simulation assists the evaluation of protection by Gypenosides in a zebrafish pain model

In recent years, due to its rapid reproduction rate and the similarity of its genetic structure to that of human, the zebrafish has been widely used as a pain model to study chemical influences on behavior. Swimming behaviors are mediated by motoneurons in the spinal cord that drive muscle contractions, therefore a knowledge of internal muscle mechanics can assist the understanding of the effects of drugs on swimming activity. To demonstrate that the technique used in our study can supplement biological observations by quantifying the contribution of muscle effects to altered swimming behaviours, we have evaluated the pain/damage caused by 0.1% acetic acid to the muscle of 5 dpf zebrafish larvae and the effect of protection from this pain/damage with the saponin Gypenosides (GYP) extracted from Gynostemma pentaphyllum. We have quantified the parameters related to muscle such as muscle power and the resultant hydrodynamic force, proving that GYP could alleviate the detrimental effect of acetic acid on zebrafish larvae, in the form of alleviation from swimming debility, and that the muscle status could be quantified to represent the degree of muscle damage due to the acetic acid and the recovery due to GYP. We have also linked the behavioral changes to alteration of antioxidant and inflammation gene expression. The above results provide novel insights into the reasons for pain-related behavioral changes in fish larvae, especially from an internal muscle perspective, and have quantified these changes to help understand the protection of swimming behaviors and internal muscle by GYP from acetic acid-induced damage.

Quercetin attenuates diabetic neuropathic pain by inhibiting mTOR/p70S6K pathway-mediated changes of synaptic morphology and synaptic protein levels in spinal dorsal horn of db/db mice

Numerous studies indicate that the changes of synaptic morphology and synaptic protein levels in spinal dorsal horn neurons contributes to the development and maintenance of neuropathic pain. Quercetin, a bioflavonoid compound, has been shown to have analgesic effect in several pain models. However, the underlying mechanism for quercetin to allieviate pain is unclear. Therefore, in this study, we observed the effect of quercetin on diabetic neuropathic pain in db/db mice and explored the underlying mechanisms. Our results showed that chronic quercetin treatment alleviated thermal hyperalgesia in db/db mice. Moreover, quercetin administration significantly reduced the total dendritic length, the number of dendritic branches, and the dendritic spine density in the spinal dorsal horn neurons of db/db mice. Meanwhile, the up-regulated expressions of synaptic plasticity-associated proteins postsynaptic density protein 95 (PSD-95) and synaptophysin in spinal dorsal horn of db/db mice were decreased by quercetin treatment. In addition, quercetin treatment reduced the phosphorylated levels of mammalian target of rapamycin (mTOR) and p70 ribosomal S6 kinase (p70S6K) in spinal dorsal horn of db/db mice. These results demonstrate that quercetin may alleviate diabetic neuropathic pain by inhibiting mTOR/p70S6K pathway-mediated changes of synaptic morphology and synaptic protein levels in spinal dorsal horn neurons of db/db mice. These findings suggest that quercetin may be a promising therapeutic drug in neuropathic pain.

Exposure to low doses of malathion during juvenile and peripubertal periods impairs testicular and sperm parameters in rats: Role of oxidative stress and testosterone

Malathion is an organophosphate insecticide used in agriculture and for controlling vector-borne diseases such as Zika. Humans can be exposed to malathion by means of ingestion of contaminated food. The juvenile and peripubertal periods are a large window of vulnerability to the action of toxic agents. The aim of the present study was to evaluate the effects of low doses of malathion during the development of testes in the juvenile and peripubertal periods in rats. For this purpose, 45 male Wistar rats (postnatal day (PND) 25) were assigned to 3 experimental groups and treated for 40 days. The animals were exposed daily to malathion 10 mg/kg (M10 group) or 50 mg/kg (M50 group) diluted in 0.9 % saline via gavage. The control group received only the vehicle. On the 40th experimental day, the rats were anaesthetized and euthanized. The blood was collected for determination of testosterone concentration. The testes were removed and weighed. Spermatozoa from the vas deferens were used for sperm morphological analysis. The testes were used for evaluation of sperm count and oxidative stress status to determine the inflammatory profile and analysis of tissue constitution. The results showed that both malathion doses reduced the sperm count and increased the number of abnormal sperms. Furthermore, both doses altered the spermatogenetic process, delayed spermiogenesis, reduced the Leydig and Sertoli cell number and increased the thickness of tunica albuginea. The M10 group presented increased IL-10 levels and reduced GSH levels. These parameters did not change in the M50 group. However, the M50 group showed an increase in the number of abnormal seminiferous tubules, a decrease in plasma testosterone concentration and an increase in lipid peroxidation in the testes. In conclusion, the exposure to low doses of malathion during juvenile and peripubertal development resulted in testicular toxicity and compromised the testicular morphology and function.

Analgesic, anti-inflammatory and antipyretic activities of ethanolic extract of stem bark of Anogeissus latifolia Roxb

Background

Stem bark of Anogeissus latifolia Roxb (family: Combretaceae) is used traditionally and ethnomedicinally to alleviate pain, inflammation and fever conditions. The current study investigates the analgesic, anti-inflammatory and antipyretic activities of ethanolic extract of stem bark of Anogeissus latifolia Roxb.

Method

The HPLC studies were carried out to standardize the stem bark ethanolic extract of Anogeissus latifolia (ALEE) using ellagic acid as a marker. ALEE was screened for analgesic (formalin-induced pain and acetic acid induced writhing) and anti-inflammatory (formalin and carrageenan-induced paw oedema) activities in Wistar rats. Before 1 h of acetic acid or formalin or carrageenan injection, rats were orally fed with ALEE (100, 200 and 400 mg/kg), Aspirin (100 mg/kg) or Indomethacin (10 mg/kg). Antipyretic effect was studied in brewer’s yeast-induced pyrexia model in rats using Paracetamol (100 mg/kg) as a standard drug.

Results

HPLC analysis of ALEE revealed the presence of ellagic acid. ALEE treatment (200 and 400 mg/kg) significantly inhibited pain response in both models. ALEE treatments prevented the raise of paw volume in both in-vivo models with percent inhibition of 44.40 and 46.21, respectively at 5 h. ALEE also showed a significant reduction of yeast-induced pyrexia till 4 h of treatment.

Conclusion

ALEE exhibited analgesic, anti-inflammatory and antipyretic property in experimental models and validates traditional use of ALEE in pain, inflammation and fever.

Analgesic activity and mechanism of action of a Beta vulgaris dye enriched in betalains in inflammatory models in mice

Evidence demonstrates the pronounced anti-inflammatory activity of a beetroot (Beta vulgaris) dye enriched in betalains obtained using precipitation with ethanol. Herein, we expand upon our previous observations and demonstrate the analgesic and antioxidant effect of betalains. Betalains [10-1000 mg/kg; intraperitoneal route (i.p.)] diminished acetic acid- and PBQ-induced abdominal contortions, and the overt pain-like behaviour induced by complete Freund`s adjuvant (CFA) and formalin (intraplantar; i.pl.) injection. Moreover, betalains (100 mg/kg) administered by various routes [i.p. or subcutaneous (s.c.)] or as a post-treatment reduced carrageenin- or CFA-induced hyperalgesia. Mechanistically, betalains mitigated carrageenin-induced tumour necrosis factor-alpha (TNF-α), interleukin (IL)-1β, superoxide anion levels, and lipid peroxidation. Betalains also stopped the depletion of reduced glutathione (GSH) levels and ferric reducing ability produced by carrageenin, as well as upregulated Nrf2 and Ho1 transcript expression in the plantar tissue of mice. Furthermore, betalains showed hydroxyl radical, 2,2'-azino-di-(3-ethylbenzthiazoline-6-sulphonic acid) radical (ABTS⁺), and 2,2-diphenyl-1-picryl-hydrazyl radical (DPPH•) scavenging ability and iron-chelating activity (bathophenantroline assay), and inhibited iron-independent and iron-dependent lipid peroxidation (LPO) in vitro. Finally, betalains-treated bone marrow-derived macrophages exhibited lower levels of cytokines (TNF-α and IL-1β), and superoxide anion levels and nuclear factor kappa B (NF-κB) activation following lipopolysaccharide (LPS) stimulation. Therefore, this betalain-rich dye extracted using a novel precipitation approach presents prominent analgesic effect in varied models of pain by mechanisms targeting cytokines and oxidative stress.

Therapeutic Potential of Flavonoids in Pain and Inflammation: Mechanisms of Action, Pre-Clinical and Clinical Data, and Pharmaceutical Development

Pathological pain can be initiated after inflammation and/or peripheral nerve injury. It is a consequence of the pathological functioning of the nervous system rather than only a symptom. In fact, pain is a significant social, health, and economic burden worldwide. Flavonoids are plant derivative compounds easily found in several fruits and vegetables and consumed in the daily food intake. Flavonoids vary in terms of classes, and while structurally unique, they share a basic structure formed by three rings, known as the flavan nucleus. Structural differences can be found in the pattern of substitution in one of these rings. The hydroxyl group (-OH) position in one of the rings determines the mechanisms of action of the flavonoids and reveals a complex multifunctional activity. Flavonoids have been widely used for their antioxidant, analgesic, and anti-inflammatory effects along with safe preclinical and clinical profiles. In this review, we discuss the preclinical and clinical evidence on the analgesic and anti-inflammatory proprieties of flavonoids. We also focus on how the development of formulations containing flavonoids, along with the understanding of their structure-activity relationship, can be harnessed to identify novel flavonoid-based therapies to treat pathological pain and inflammation.

Molecular Hybrids of N-Phthaloylglycyl Hydrazide and Hydrazinecarbothioamide with Anti-inflammatory and Anti-oxidant Activities

BACKGROUND

Oxidative stress due to high levels of reactive organic species is the cause of the progression of inflammation in various diseases. The molecules possessing both anti-inflammatory and antioxidant activity can be the promising key to treat inflammatory diseases. Phthalimide and hydrazinecarbothioamide are anti-inflammatory and anti-oxidant pharmacophores.

OBJECTIVE

Molecular hybrids possessing above two pharmacophores were designed. A series of N-phenyl substituted 2-(2-(1,3-dioxoisoindolin-2-yl)acetyl)-N-phenylhydrazine-1-carbothioamide (CGS compounds) was synthesized and evaluated for biological activities.

METHODS

N-phthaloylglycyl hydrazide was reacted with unsubstituted/substituted phenyl isothiocyanates to yield CGS compounds. Synthesized compounds were evaluated for in vivo anti-inflammatory activity in carrageenan rat paw edema model, and in vitro anti-oxidant activity by DPPH assay. Levels of TNF-α and oxidative stress at the site of inflammation were measured. The genetic algorithm-PLS regression based QSAR model correlating the effect of N-phenyl substituent on the anti-inflammatory activity was developed. Further, the interaction of the active compound in the TNF-α binding pocket was studied by in silico docking.

RESULTS

Compound containing the 2-OCH3, 4-NO2 (CGS-5); 4-CF3 (CGS-9); 4-NO2 (CGS-3) showed significant anti-inflammatory activity (percentage inhibition of paw edema after 3 hour = 58.24, 50.38, 40.05, respectively) and potent anti-oxidant activity (IC50 =0.045, 0.998, 0.285 μg/ml, respectively). Reduced levels of TNF- α and increased levels of GSH were observed for the above three compounds. Descriptors for QSAR model identified by GA-PLS were WPSA1, Weta1unity, WDunity, SC3, VC5, MlogP, and WTPT3. The identified model was highly predictive, and value of root mean square error of prediction for internal (leave one out) and external validation was: 1.579, 1.325.

CONCLUSION

Molecular hybrids of phthalimide and hydrazinecarbothioamide were synthesized. Some of the compounds possessed promising anti-inflammatory and anti-oxidant activities.

Utilizing Liposomal Quercetin and Gallic Acid in Localized Treatment of Vaginal Candida Infections

Vulvovaginal candidiasis (VVC) is a widely spread fungal infection that causes itching, pain and inflammation at the vaginal site. Although common, currently available treatment suffers from limited efficacy and high recurrence. In addition, the growing problem of resistance to azole drugs used in current treatments emphasizes the need for superior treatment options. Antimicrobial polyphenols are an attractive approach offering multitargeting therapy. We aimed to develop novel liposomes for simultaneous delivery of two polyphenols (quercetin, Q, and gallic acid, GA) that, when released within the vaginal cavity, act in synergy to eradicate infection while alleviating the symptoms of VVC. Q was selected for its anti-itching and anti-inflammatory properties, while GA for its reported activity against Candida. Novel liposomes containing only Q (LP-Q), only GA (LP-GA) or both polyphenols (LP-Q+GA) were in the size range around 200 nm. Q was efficiently entrapped in both LP-Q and in LP-Q+GA (85%) while the entrapment of GA was higher in LP-Q+GA (30%) than in LP-GA (25%). Liposomes, especially LP-Q+GA, promoted sustained release of both polyphenols. Q and GA acted in synergy, increasing the antioxidant activities of a single polyphenol. Polyphenol-liposomes were not cytotoxic and displayed stronger anti-inflammatory effects than free polyphenols. Finally, LP-GA and LP-Q+GA considerably reduced C. albicans growth.

Antioxidant, hepatoprotective, genoprotective, and cytoprotective effects of quercetin in a murine model of arthritis

Rheumatoid arthritis is a highly debilitating inflammatory autoimmune disease which is characterized by joint destruction. The present study sought to investigate the effect of quercetin in rats with complete Freund's adjuvant-induced arthritis. Animals were divided into control/saline, control/quercetin (5 mg/kg, 25 mg/kg, and 50 mg/kg) arthritis/saline, and arthritis/quercetin (5 mg/kg, 25 mg/kg, and 50 mg/kg); the treatments were administered for 45 days. Biochemical, oxidative stress, genotoxicity, and cytotoxicity parameters were evaluated. All doses of quercetin reduced the levels of aspartate aminotransferase, thiobarbituric acid-reactive substances, and reactive oxygen species; however, only treatment with 25 or 50 mg/kg increased catalase activity. Total thiol and reduced glutathione levels were not significantly affected by the induction nor by the treatments. Genotoxicity assessed by DNA damage, and cytotoxicity through picogreen assay, decreased after treatments with quercetin. Our results present evidence of the antioxidant, cytoprotective, genoprotective and hepatoprotective, and effects of quercetin, demonstrating its potential as a candidate for coadjuvant therapy.

Euphorbia bicolor (Euphorbiaceae) Latex Phytochemicals Induce Long-Lasting Non-Opioid Peripheral Analgesia in a Rat Model of Inflammatory Pain

The negative side effects of opioid-based narcotics underscore the search for alternative non-opioid bioactive compounds that act on the peripheral nervous system to avoid central nervous system-mediated side effects. The transient receptor potential V1 ion channel (TRPV1) is a peripheral pain generator activated and sensitized by heat, capsaicin, and a variety of endogenous ligands. TRPV1 contributes to peripheral sensitization and hyperalgesia, in part, via triggering the release of proinflammatory peptides, such as calcitonin gene-related peptide (CGRP), both locally and at the dorsal horn of the spinal cord. Ultrapotent exogenous TRPV1 agonists, such as resiniferatoxin identified in the latex of the exotic Euphorbia resinifera, trigger hyperalgesia followed by long lasting, peripheral analgesia. The present study reports on the analgesic properties of Euphorbia bicolor, a relative of E. resinifera, native to the Southern United States. The study hypothesized that E. bicolor latex extract induces long-lasting, non-opioid peripheral analgesia in a rat model of inflammatory pain. Both inflamed and non-inflamed adult male and female rats were injected with the methanolic extract of E. bicolor latex into the hindpaw and changes in pain behaviors were reassessed at various time points up to 4 weeks. Primary sensory neuron cultures also were treated with the latex extract or vehicle for 15 min followed by stimulation with the TRPV1 agonist capsaicin. Results showed that E. bicolor latex extract evoked significant pain behaviors in both male and female rats at 20 min post-injection and lasting around 1–2 h. At 6 h post-injection, analgesia was observed in male rats that lasted up to 4 weeks, whereas in females the onset of analgesia was delayed to 72 h post-injection. In sensory neurons, latex extract significantly reduced capsaicin-evoked CGRP release. Blocking TRPV1, but not opioid receptors, attenuated the onset of analgesia and capsaicin-induced CGRP release. Latex was analyzed by mass spectrometry and eleven candidate compounds were identified and reported here. These findings indicate that phytochemicals in the E. bicolor latex induce hyperalgesia followed by peripheral, non-opioid analgesia in both male and female rats, which occurs in part via TRPV1 and may provide novel, non-opioid peripheral analgesics that warrant further examination.

Myrtus Polyphenols, from Antioxidants to Anti-Inflammatory Molecules: Exploring a Network Involving Cytochromes P450 and Vitamin D

Inflammatory response represents one of the main mechanisms of healing and tissue function restoration. On the other hand, chronic inflammation leads to excessive secretion of pro-inflammatory cytokines involved in the onset of several diseases. Oxidative stress condition may contribute in worsening inflammatory state fall, increasing reactive oxygen species (ROS) production and cytokines release. Polyphenols can counteract inflammation and oxidative stress, modulating the release of toxic molecules and interacting with physiological defenses, such as cytochromes p450 enzymes. In this paper, we aimed at evaluating the anti-inflammatory properties of different concentrations of Myrtus communis L. pulp and seeds extracts, derived from liquor industrial production, on human fibroblasts. We determined ROS production after oxidative stress induction by H₂O₂ treatment, and the gene expression of different proinflammatory cytokines. We also analyzed the expression of CYP3A4 and CYP27B1 genes, in order to evaluate the capability of Myrtus polyphenols to influence the metabolic regulation of other molecules, including drugs, ROS, and vitamin D. Our results showed that Myrtus extracts exert a synergic effect with vitamin D in reducing inflammation and ROS production, protecting cells from oxidative stress damages. Moreover, the extracts modulate CYPs expression, preventing chronic inflammation and suggesting their use in development of new therapeutic formulations.

First ethnobotanical inventory and phytochemical analysis of plant species used by indigenous people living in the Maromizaha forest, Madagascar

ETHNOPHARMACOLOGICAL RELEVANCE

Characterized by one of the highest rates of endemism and biodiversity in the world, Madagascar provides a wide variety of medicinal plants, that could represent a potential source of new drugs. The main aim of this study was to investigate the potential medicinal properties of the plant species used by indigenous people in Maromizaha forest and to provide the first ethnobotanical inventory of the area.

MATERIALS AND METHODS

Data were collected through open semi-structured interviews with local informants, the reported plants were collected and identified to create a specimen herbarium. Informant Consensus Factor (ICF) was calculated for each ailment category mentioned in the use-reports. A selection of seven medicinal plants was submitted to phytochemical and antimicrobial analysis. The results were discussed and compared with those described in ethnobotanical and pharmacological literature.

RESULTS

One hundred and three villagers were interviewed and a total of 509 use-reports were recorded. Information on 117 plant species belonging to 57 botanical families were provided. 12 categories of indigenous uses were recognized, among them the higher ICF values were recorded for cardiovascular complaints (0.75), general and unspecific diseases (0.74), digestive disorders (0.69), and diseases of the skin (0.55). The traditional medicinal uses of 18 species (15 endemic) were described for the first time. In total, 22 different bioactive compounds were identified; polyphenols, monoterpenes, organic acids, and vitamin C were observed in the chemical composition of all the analyzed samples. Macaranga perrieri showed the highest values of both total polyphenolic compounds and antioxidant activity. Antimicrobial activity was observed in leaf and bark extracts of Dilobeia thouarsii.

CONCLUSION

These results confirmed the importance of investigating the traditional use of plant species, suggesting the crucial role of ethnobotanical studies for rural development, biodiversity conservation, and the sustainable use of plant resources in the studied area.

Sleep restriction during peripuberty unbalances sexual hormones and testicular cytokines in rats

Spermatogenesis and steroidogenesis are not fully established during puberty. Especially during this period, children and adolescents may be chronically sleep deprived due to early school hours and constant exposure to artificial light and interactive activities. We have previously shown that sleep restriction (SR) during peripuberty impairs sperm motility and has consequences on epididymal development in rats. Thus, this study aimed to evaluate the effect of SR during peripuberty on sexual hormones and its impact on testicular tissue. Rats were subjected to 18 h of SR per day for 21 days or were maintained as controls (C) in the same room. The circulating luteinizing hormone levels were decreased in SR rats without changes in the follicle stimulating hormone levels. Plasma and intratesticular testosterone and corticosterone in the SR group were increased in relation to C group. These alterations impair testicular tissue, with decreased IL-1β, IL-6, and TNFα levels in the testis and diminished seminiferous epithelium height and Sertoli cell number. SR also increased testicular lipid peroxidation with no alteration in antioxidant profiles. There were no significant changes in sperm parameters, seminiferous tubule diameter, histopathology, spermatogenesis kinetics, neutrophil and macrophage recruitment, and IL-10 concentration. Our results show that SR unbalances sexual hormones and testicular cytokines at a critical period of sexual maturation. These changes lead to lipid peroxidation in the testes and negatively influence the testicular tissue, as evidenced by diminished seminiferous epithelium height-with apoptosis of germinative cell-and Sertoli cell number.

Recent development in antihyperalgesic effect of phytochemicals: anti-inflammatory and neuro-modulatory actions

INTRODUCTION

Pain is an unpleasant sensation triggered by noxious stimulation. It is one of the most prevalent conditions, limiting productivity and diminishing quality of life. Non steroidal anti inflammatory drugs (NSAIDs) are widely used as pain relievers in present day practice as pain is mostly initiated due to inflammation. However, due to potentially serious side effects, long term use of these antihyperalgesic drugs raises concern. Therefore there is a demand to search novel medicines with least side effects. Herbal products have been used for centuries to reduce pain and inflammation, and phytochemicals are known to cause fewer side effects. However, identification of active phytochemicals of herbal medicines and clear understanding of the molecular mechanism of their action is needed for clinical acceptance.

MATERIALS AND METHODS

In this review, we have briefly discussed the cellular and molecular changes during hyperalgesia via inflammatory mediators and neuro-modulatory action involved therein. The review includes 54 recently reported phytochemicals with antihyperalgesic action, as per the literature available with PubMed, Google Scholar and Scopus.

CONCLUSION

Compounds of high interest as potential antihyperalgesic agents are: curcumin, resveratrol, capsaicin, quercetin, eugenol, naringenin and epigallocatechin gallate (EGCG). Current knowledge about molecular targets of pain and their regulation by these phytochemicals is elaborated and the scope of further research is discussed.

Quercetin attenuates zymosan-induced arthritis in mice

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by articular lesions, recruitment of inflammatory cells and increased levels of pro-inflammatory cytokine. The intra-articular administration of zymosan is an experimental model that promotes inflammatory parameters resembling RA. Therefore, this model was used to investigate the efficacy of quercetin as a treatment of articular inflammation. Treatment with quercetin dose-dependently reduced zymosan-induced hyperalgesia, articular edema and the recruitment of neutrophils to the knee joint cavity. Histological analysis confirmed that quercetin inhibited zymosan-induced arthritis. The treatment with quercetin also inhibited zymosan-induced depletion of reduced glutathione (GSH) levels, TNFα and IL-1β production, and gp91^phox, prepro-endothelin-1 (preproET-1), and cyclooxygenase-2 mRNA expression. These molecular effects of quercetin were related to the inhibition of the nuclear factor kappa-B and induction of Nuclear factor erythroid 2- related factor (Nrf2)/home oxygenase (HO-1) pathway. Thus, quercetin exerted anti-inflammatory, analgesic and antioxidant effects in experimental arthritis, suggesting quercetin is a possible candidate for arthritis treatment.

Orofacial antinociceptive effect of Mimosa tenuiflora (Willd.) Poiret

Mimosa tenuiflora (Willd.) Poiret, popularly known in Brazil as "jurema-preta" is widely used against bronchitis, fever, headache and inflammation. Its antioxidant, anti-inflammatory and antinociceptive potential has already been reported. To assess the orofacial antinociceptive effect of M. tenuiflora, ethanolic extracts of M. tenuiflora (leaves, twigs, barks and roots) were submitted to in vitro tests of antioxidant activity. The extract with the highest antioxidant potential was partitioned and subjected to preliminary chemical prospecting, GC-MS, measurement of phenolic content and cytotoxicity tests of the fraction with the highest antioxidant activity. The nontoxic fraction with the highest antioxidant activity (FATEM) was subjected to tests of acute and chronic orofacial nociception and locomotor activity. The possible mechanisms of neuromodulation were also assessed. The EtOAc fraction, obtained from the ethanolic extract of M. tenuiflora barks, was the one with the highest antioxidant potential and nontoxic (FATEM), and Benzyloxyamine was the major constituent (34.27%). FATEM did not alter the locomotor system of mice and reduced significantly the orofacial nociceptive behavior induced by formalin, glutamate, capsaicin, cinnamaldehyde or acidic saline compared to the control group. FATEM also inhibited formalin- or mustard oil-induced temporomandibular nociception. In addition, it also reduced mustard oil-induced orofacial muscle nociception. However, FATEM did not alter hypertonic saline-induced corneal nociception. Neuropathic nociception was reversed by treatment with FATEM. The antinociceptive effect of FATEM was inhibited by naloxone, L-NAME and glibenclamide. FATEM has pharmacological potential for the treatment of acute and neuropathic orofacial pain and this effect is modulated by the opioid system, nitric oxide and ATP-sensitive potassium channels. These results lead us to studies of isolation and characterization of bioactive principles.

The flavonoid quercetin inhibits titanium dioxide (TiO2)-induced chronic arthritis in mice

Titanium dioxide (TiO₂) is a common component of orthopedic prosthesis. However, prosthesis wear releases TiO₂, which induces inflammation and osteolysis in peri-prosthetic tissues. Quercetin is a flavonoid widely present in human diet, which presents biological activities such as antinociceptive, anti-inflammatory and antioxidant effects. Therefore, the effect of intraperitoneal treatment with quercetin in TiO₂-induced arthritis model was evaluated. In the first set of experiments, mice received injection of TiO₂ (0.1-3 mg/knee joint) and articular mechanical hyperalgesia, edema and histopathology analysis were performed in a 30 days protocol. The dose of 3 mg of TiO₂ showed the most harmful effect, and was chosen to the following experiments. Subsequently, mice received 3 mg of TiO₂ followed by post-treatment with quercetin during 30 days. Quercetin (10-100 mg/kg) inhibited in a dose-dependent manner TiO₂-induced knee joint mechanical hyperalgesia, edema and leukocyte recruitment and did not induce damage in major organs such as liver, kidney and stomach. The dose of 30 mg/kg was chosen for the subsequent analysis, and reduced histopathological changes such as leukocyte infiltration, vascular proliferation and synovial hyperplasia (pannus formation) on day 30 after TiO₂ challenge. The protective analgesic and anti-inflammatory mechanisms of quercetin included the inhibition of TiO₂-induced neutrophil and macrophage recruitment, proteoglycan degradation, oxidative stress, cytokine production (TNF-α, IL-1β, IL-6, and IL-10), COX-2 mRNA expression, and bone resorption as well as activation of Nrf2/HO-1 signaling pathway. These results demonstrate the potential therapeutic applicability of the dietary flavonoid quercetin to reduce pain and inflammatory damages associated with prosthesis wear process-induced arthritis.

Quercetin alleviates thermal and cold hyperalgesia in a rat neuropathic pain model by inhibiting Toll-like receptor signaling

Neuropathic pain is caused by lesion or disease of the nervous system, which results in abnormal spontaneous and evoked pain. It's common in clinical practice and greatly impairs the life quality of patients, but the effective treatment is still lacking. In this study, we aimed to explore the effect of quercetin (QUE) on neuropathic pain and the underlying mechanisms. Spinal nerve ligation (SNL) was performed in Sprague Dawley rats to establish the neuropathic pain model. Single or continuous oral administration of QUE after the operation or continuous administration before the operation was applied to evaluate the effects of QUE on SNL-induced thermal and cold hyperalgesia. Dorsal root ganglions from these rats were harvested to analyze the expression levels of some inflammatory mediators. Primary cultured astrocytes and HEK293 cells were used to further explore the downstream signaling pathways of QUE. Both single and continuous oral administration of QUE dose-dependently alleviated SNL-induced thermal and cold hyperalgesia. Pre-administration also attenuated neuropathic pain symptoms. Meanwhile, SNL-induced increase in protein or mRNA levels of some inflammatory mediators could be down-regulated by QUE treatment. Furthermore, QUE reduced the phosphorylation of TAK1, IKK and JNK2 in cultured astrocytes. Moreover, luciferase assay in HEK293 cells showed that QUE dose-dependently inhibited NF-κB activity only via TAK1. QUE exerts anti-inflammatory effects and alleviates neuropathic pain through the inhibition of Toll-like receptor signaling pathway. It could shed some light on the potential applications of QUE in chronic pain therapy.

Quercetin inhibits gout arthritis in mice: induction of an opioid-dependent regulation of inflammasome

We investigated the anti-inflammatory and analgesic effects of quercetin in monosodium urate crystals (MSU)-induced gout arthritis, and the sensitivity of quercetin effects to naloxone, an opioid receptor antagonist. Mice were treated with quercetin, and mechanical hyperalgesia was assessed at 1-24 h after MSU injection. In vivo, leukocyte recruitment, cytokine levels, oxidative stress, NFκB activation, and gp91phox and inflammasome components (NLRP3, ASC, Pro-caspase-1, and Pro-IL-1β) mRNA expression by qPCR were determined in the knee joints at 24 h after MSU injection. Inflammasome activation was determined, in vitro, in lipopolysaccharide-primed macrophages challenged with MSU. Quercetin inhibited MSU-induced mechanical hyperalgesia, leukocyte recruitment, TNFα and IL-1β production, superoxide anion production, inflammasome activation, decrease of antioxidants levels, NFκB activation, and inflammasome components mRNA expression. Naloxone pre-treatment prevented all the inhibitory effects of quercetin over MSU-induced gout arthritis. These results demonstrate that quercetin exerts analgesic and anti-inflammatory effect in the MSU-induced arthritis in a naloxone-sensitive manner.

Quercetin inhibits acid-sensing ion channels through a putative binding site in the central vestibular region

Acid-sensing ion channels (ASICs) are associated with many pathophysiological processes, such as neuronal death during ischemic stroke, epileptic seizure and nociception. However, there is a dearth of ASIC-specific therapeutic blockers. Here we report that quercetin, a plant flavonoid, which is known for its neuroprotective effect, reversibly inhibits homomeric rat ASIC1a, ASIC2a and ASIC3 with an IC₅₀ of about 2µM. Also, quercetin prevents low pH-induced intracellular calcium rise and cell death in HEK-293 cells, which have endogenous expression of ASIC1a and 2a. The inhibitory effect of quercetin on ASICs is not due to membrane perturbation, as it did not have any effect on other channels, like NMDA receptor, GABA_A receptor and P2X4 receptor. Unlike quercetin, another flavonoid resveratrol had no effect on ASIC1a. Computational analysis revealed that quercetin binds to the channel in a cavity at the central vestibule, lined by several charged residues like Q276, R369, E373 and E416 in ASIC1a. Mutation of Arg369 to Ala or Glu416 to Gln abolished the inhibitory effect of quercetin on rat ASIC1a completely, while Glu373 to Gln showed reduced sensitivity. Our results raise the possibility of using quercetin for targeting ASICs in vivo.

Comparison of antioxidant activities of fractionated extracts from seedlings and herb of Chelidonium majus L. using DPPH, ABTS and FRAP methods

Introduction: Our study is a part of a trend of studies on the antioxidative properties of Chelidonium majus extracts or their fractions suggesting that antioxidant activities may depend on total flavonoid and/or alkaloid contents.

Objective: This study focused on the examination of antioxidative activities of full water extract, non-protein fraction and protein fraction of the extract from aerial parts of mature plants and young seedlings.

Methods: Total flavonoid and alkaloid contents were evaluated by spectrometric methods. Quantitative determination of chelidonine, coptisine, sanquinarine, berberine was made by HPLC-UV. The antioxidative activities were evaluated using (1) 2,2-diphenyl-1-picrylhydrazyl (DPPH), (2) 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging and (3) ferric reducing antioxidant power (FRAP) methods.

Results: All concentrations of herb extracts exhibited higher antioxidant capacities than extract from seedlings. Two antioxidant tests (DPPH, FRAP) showed that full water extract from herb had the highest antioxidant activity, while its non-protein fraction and protein fraction showed lower antioxidant activity. It was found that the full water extract from herb contained the highest concentrations of flavonoids and alkaloids when compared with other samples.

Conclusion: Our findings suggest that chelidonine and coptisine especially could be responsible for the observed changes in the extract antioxidant activity, because these alkaloids were determined in the highest concentration in full water extract from herb. It cannot be also excluded that the observed variables values between extracts and their fractions from herb or from seedlings may also be the result of interactions between flavonoids and other chemical compounds.